div{
	<b>border-color</b> : 	<i>transparent</i> 				<em>// 透明</em>
					red
					#ff0000
					rgba(0,0,0,.1)
					red blue green yellow		<em>// <s>上-右-下-左</s> 边的颜色</em>
	<em># 设置单边颜色</em>
	<b>border-top-color</b>: 			red
	<b>border-right-color</b>: 		red
	<b>border-bottom-color</b>: 		red
	<b>border-left-color</b>: 			red
}